In applications of the radio frequency identification (RFID) technology, an approach of detecting certain apparatuses via a time slot detection is quite common. For example, an RFID system comprises an RFID reader and a plurality of RFID tags each comprising a unique identification code (UID code). The RFID reader accesses the UID code of each of the plurality of RFID tags according to an RFID communication protocol to identify the respective RFID tag. When a plurality of RFID tags, e.g., five RFID tags 1 to 5, become close to an inductor of a door control system, the inductor generates a plurality of time slots, e.g., three time slots comprising namely a first time slot, a second time slot and a third time slot, simultaneously informs the five RFID tags of the time slot number of three, and requests the five RFID tags to reply to the inductor during the time slots. Accordingly, the RIFD tags generate random codes via electric energy induced by the inductor, calculate the number of the time slots, and reply to the inductor during the time slots corresponding to the random codes. When only one RFID tag replies to the inductor during one time slot, the inductor successfully identifies the RFID tag and requests the RFID tag to transmit a reply report comprising the UID code of the RFID tag. When the number of the time slots is smaller than that of the RFID tags, a collision occurs when a plurality of RFID tags reply to the same RFID reader, i.e., when two or more RFID tags simultaneously reply to the RFID reader during a single time slot. At this time, the plurality of RFID tags replying to the RFID reader during the time slot keep replying during the time slot in a next stage until all RFID tags are identified by the RFID reader.
Continuing with the foregoing example, suppose the five RFID tags reply to the inductor according to the random codes, i.e., the RFID tag 4 replies to the inductor during the first time slot, the RFID tags 1 and 2 reply to the inductor during the second time slot, and the RFID tags 3 and 5 reply to the inductor during the third time slot. In this stage of time slots, the inductor can only successfully identify the RFID tag 4 that replies during the first time slot, while other RFID tags are similarly identified through their UID codes during the time slots of the next stage until all RFID tags are identified by the inductor.
Generally speaking, the architecture implementing time slots to detect apparatuses is entirely realized by hardware. FIG. 1 shows a block diagram of hardware of a conventional time slot detecting system 10. The conventional time slot detecting system 10 comprises a timer 12, a time slot controller 14 and a communication protocol processor 16. When the conventional time slot detecting system 10 begins to perform a time slot detection, the time slot controller 14 defines a length of a time slot period on the timer 12 via a universal input/output bus 18. When timing each time slot, the timer 12 sends a time slot start signal (e.g., a time slot interrupt signal INT_S) or uses a poll approach to inform the time slot controller 14. Upon sending the time slot interrupt signal INT_S, the timer 12 starts timing a period. At this point, the time slot controller 14 triggers the communication protocol processor 16 with an enable signal S_EN, such that the communication protocol processor 16 begins to process operations associated with an RFID communication protocol. When the operations associated with the RFID communication protocol are processed, the communication protocol processor 16 replies to the time slot controller 14 with a completion signal SC, and thus the time slot controller 14 deactivates the communication protocol processor 16 with a disable signal S_ENB.
However, the time slot detecting system 10 realized by hardware has a disadvantage of lacking design flexibility. Since circuits inside the communication protocol processor 16 and the time slot controller 14 are designed in compliance with a certain RFID communication protocol, when the RFID communication protocol or some detailed specification of the RFID communication protocol needs to be changed, corresponding hardware circuits need to be redesigned to again comply with the changed RFID communication protocol, resulting in inconvenience of design adjustment.